The present invention relates to machines for testing and measuring parts, and, more particularly, to machines for measuring round or ring-shaped parts.
As explained in U.S. Pat. No. 5,711,083, issued Jan. 27, 1998 to the assignee of the present application, machining facilities commonly must inspect both size and out-of-roundness condition on internal and external diameters of ring-shaped parts. In the past, this has been performed by many of the prior art gages. Due to the way that these gages were designed, there were many inherent problems that were accepted as common practice when one used this type of gage.
These measurement problems were significantly reduced or even eliminated with the introduction of the gage set disclosed in aforementioned U.S. Pat. No. 5,711,083 (the xe2x80x9coriginal gage setxe2x80x9d). The present application is for a new style of swing gage, in combination with a unit to keep the swing gage on the actual centerline of the part to be measured.
There are several significant differences between the original gage set and the present one disclosed in this application. First and foremost is the incorporation of a unique type of bearing to drive the probe. Prior art gages use a spring probe that mechanically interfaces with a plunger on a dial indicator. The present design uses a profile rail and carriage bearing setup. This concept has never been used in this type of application before. To put this application in layman""s terms, one should think of a train""s wheels going down a track that is fastened to the ground. This concept has now been reversed. The train is fastened to the ground, and the track is running along the wheels of the train. No other gage has this design. Additionally, another distinct feature of this design is that the bearing and profile rail are permanently aligned for virtually maintenance free operation.
Another unique feature on the present swing gage is the use of roller bearings on the contact probes. Prior art gages have metal-to-metal contact between the surface of the probe and the part being measured. This can cause scoring of the part, particularly if the part to be measured is made from a soft material or is coated. This new concept of using a roller bearing makes for a virtually friction-free environment between the part being measured and the surface of the contact probes. Side supports are attached to each side of the swing gage to minimize or eliminate the sagging condition that occurs in prior art gages. Furthermore, a datum plate (which is attached to the center post of the unit that centers the gage) aids in the inspection of parts having irregular top faces, and also eliminates the application of weight to the top of the part. This prevents the part from being distorted, a condition that could lead to a false measurement. This unit can also be slid up and down the center protruding post to check for taper in the part being measured.
Still further, the construction of the swing gage allows for minimal thermal expansion due to environmental conditions. Prior art gages are susceptible to thermal expansion because body temperature can effect the accuracy of measurement.
Also, a support device connected to the contact probe prohibits deflection of the probe when it is extended out. Prior art gages do not have this feature. This can severely effect the measurement as testing has proven.
Finally, a new concept to enhance the ability to locate the swing gage at the actual centerline of the part has been designed. It incorporates some of the features of the original gage set, but with some added features. This new design has the ability to locate the ring-type part to be measured by either the outside diameter or the inside diameter. The old design could only locate the part from the inside diameter. Also, thin or flexible rings can be inspected by spinning the part around the reference-end contact probe. This is important because the spring pressure of prior art gages could easily distort a thin ring. These added features greatly multiply the potential applications for this gage set.
An adjustable gage is positionable at the actual centerline of a ring-shaped part, and quickly and accurately measures the size of the part and certain conditions of the part, such as out-of-roundness. According to a preferred embodiment, the gage of the present invention comprises two separate components. The first component is an xe2x80x9cEZ-MATE(trademark)xe2x80x9d centerline hub that comprises a centrally-located body and a cylindrical post protruding up vertically from the center of the body. The unit has three slots formed on the top surface into which three position jaws are adjustably positioned.
The second component of the present invention is a DIRECT-STYLE(trademark) swing gage that comprises a pair of cylindrical slide bars that are oriented in parallel. Front and rear blocks are positioned on the corresponding ends of the two slide bars. The blocks are adjustable to predetermined positions on the corresponding ends of the two slide bars. The front block has associated with it a dial or electronic indicator and a corresponding movable probe that is driven and guided by a profile rail and carriage bearing (e.g., the probe is attached to the profile rail, which is slidably disposed within the carriage bearing). The probe has a roller bearing on the end that will come into contact with the part to be measured. The dial or electronic indicator visually indicates any movement of the probe. The rear block also has a probe and a roller bearing associated therewith; however this probe is in a fixed position.
In use, the position jaws of the EZ-MATE(trademark) centerline hub are adjusted using, e.g., a depth micrometer or vernier calipers, to the approximate inner or outer diameter of the part to be located within. The part to be checked is then placed over the top and positioned within the three position jaws. This will guide the part into position, thereby creating an actual centerline between the part and the centerline post of the EZ-MATE(trademark) centerline hub.
Next, after setting the contact probes at an appropriate distance from one another, whether it be for an outside or an inside diameter, the two parallel slide bars of the DIRECT-STYLE(trademark) swing gage are straddled over the centerline post such that the post is located in the slotted opening between the two bars. The roller bearings associated with the contact probes will come in contact with the part to be measured.
To check the size and out of roundness of the part, the user merely rotates the DIRECT-STYLE(trademark) swing gage around the centerline post of the EZ-MATE(trademark) centerline hub by grasping either of the vertical swivel handles that protrude from the rear block. As the DIRECT-STYLE(trademark) swing gage rotates, the roller bearings that are attached to the probes are in contact with inner or outer surface of the part. These roller bearings will rotate around the part surface and the contact probe. The probe on the front block will move the profile rail in and out along the carriage bearing that is attached to the front block and will push the plunger on the indicator in and out. By observing this movement on the indicator, the user can arrive at a quick and accurate measurement and a determination of whether the part is within the dimensional specifications.